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Biologists Watch Steelhead Return After Historic Dam Removal

Sep 7, 2017 at 3:00pm

Lindsey Hoshaw, KQED Science

The Sam Clemente, an aging, 106-foot tall concrete dam blocked the steelhead’s path upstream, but removal of the dam has allowed the fish to return.

The San Clemente Dam was 95 percent full of sediment and at risk for failure during an earthquake, which would have sent more than a million tons of sediment and debris hurling toward 1,500 structures— including homes—downstream. When bulldozers crumbled the 94-year-old structure in 2015, it became the largest dam removal project in California history.

Removing the dam served a dual purpose: to dislodge a seismic hazard and restore the landscape, allowing endangered steelhead, lamprey and endangered red-legged frogs to return.